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tures of these systems may be ideal for biomedical applications in which one desires to deliver cells into the body for a therapeutic purpose (e.g., regeneration of tissues or organs). [25,26] Experimental Sodium alginate (M w = 300 000; Pronova Biopolymers, Norway) was dissolved in 2-(N-morpholino)ethanesulfonic acid (Sigma) buffer (pH 6.5, 0.3 M NaCl) at room temperature, and the peptide was added to the alginate in the presence of N-hydroxysulfosuccinimide (Pierce) and 1-ethyl-3-(dimethylaminopropyl) carbodiimide (Aldrich). The peptide with a sequence of (glycine) 4 ±argi-nine±glycine±aspartic acid±serine±proline (G 4 RGDSP) was synthesized at the University of Michigan Protein and Carbohydrate Structure Core facility. The peptide-modified alginate was purified by extensive dialysis against distilled water for 3 days (molecular weight cut-off, 3500) and activated charcoal-treatment, and sterilized through a 0.22 lm filter. The DS of RGD peptides coupled to the alginate backbone was previously determined using radiolabeled RGD peptides as a tracer molecule [9]. Non-modified alginate (no peptide) was prepared in the same manner as the RGD-modified alginate with the exception that no peptide was added to the reaction.MC3T3-E1 mouse calvarial preosteoblasts were cultured in a-minimum essential media (Hyclone), containing 10 % fetal calf serum (Hyclone) and 100 units mL ±1 penicillin-streptomycin (Gibco). The cells were mixed with alginate solutions using two syringes and a female connector, and incubated at 37 C under 5 % CO 2 atmosphere for 30 min before testing. The final concentration of alginate solutions was fixed at 1 wt.-% and cell concentrations were varied in the range from 0.25 to 1.50 10 8 cells mL ±1 . A controlled stress rheometer (C-VOR 120, Bohlin Instrument) with a coneand-plate (20 mm diameter plate, 4 cone angle) fixture was used to measure the dynamic modulus of alginate solutions in the absence or presence of cells as a function of frequency in the range from 0.01 to 1 Hz. The gap opening at the apex of the cone and plate was set to 150 lm, and the stress amplitude was fixed at 0.05 Pa as it has been found to be well within the linear stress amplitude response regime. The samples and loading apparatus were completely covered with a solvent trap to prevent the evaporation of water during the measurement. Temperature control was achieved within ± 0.1 C, and the strain was 0.1 %.

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A novel selenium-microporous carbon composite was synthesized and exhibited ultrastable cycling performance for rechargeable lithium–selenium batteries.